||Design and Implementation of Robust Congestion Controllers for TCP /AQM Communication Networks
||Department of Engineering Science
Robust stochastic control
Variable structure control
Linear matrix inequality (LMI)
Improved genetic algorithm
Nonlinear output feedback
Communication network is an essential part for many applications in science and engineering. In particular, based on different network architectures such as various nodes, transmission links and traffic sources, the Internet becomes a global network connecting millions of users and hosts. Unfortunately, the heterogeneity and the large scale in current networks give rise to complexity and difficulty for network management and control. Moreover, the quality of service (QoS) cannot be guaranteed since the number of users is increasing rapidly and there is some unpredictable interference in the networking environment. Therefore, traffic congestion turns out to be one of the major communication problems in Internet. Consequently, how to avoid congestions at bottleneck nodes by regulating the traffic flow and achieve the better performance has been an important issue over the last decade.
In this dissertation, the robust congestion controller design and implementation problems are investigated for TCP communication networks. Firstly, a rate-based non-linear TCP network system with a saturated input is addressed. Based on variable structure control (VSC) and nonlinear output feedback approaches, different kinds of active queue management (AQM) controllers are presented to achieve the desired queue size and to guarantee the asymptotic stability of the closed-loop system. Secondly, the linear feedback congestion controller design for nonlinear window-based time-delay TCP network system with input saturation is discussed. An improved genetic algorithm (GA) based Proportional-Integral-Derivative (PID) controller is proposed to guarantee the performances for TCP/AQM networks. State feedback control strategies are developed for the linearized time-delay TCP/AQM model with input saturation. Thirdly, due to the stochastic properties of the communication network, a robust stochastic AQM controller is proposed to guarantee the robustly asymptotically stable in the mean square applying the Lyapunov–Krasovskii functional approach and the linear matrix inequality (LMI) technique, while achieving the prescribed H-infinite disturbance rejection attenuation level of the closed-loop stochastic TCP/AQM system. Finally, based on the Linux platform, the proposed congestion controllers has been implemented to verify the theoretical results. Some illustrative examples performed in the NS2 are given to demonstrate the effectiveness of our main results.
English Abstract II
Table of Contents V
List of Tables IX
List of Figures X
Chapter 1 Introduction 1
1.1 Congestion Control for TCP Communication Network 1
1.2 Overview of Previous Work 3
1.3 Problem Describe and Motivation 7
1.4 Brief Sketch of the Contents 8
Chapter 2 Stabilization of Rate-Based TCP/AQM System 11
2.1 Introduction 11
2.2 Nonlinear Rate-Based TCP Dynamics 12
2.3 Variable Structure Controller Design 13
2.3.1 Problem Formulation 13
2.3.2 Main Result 15
2.3.3 Illustrative Examples 15
2.4 Backstepping Controller Design 23
2.4.1 Problem Formulation 23
2.4.2 Main Results 25
2.5 Input-Output Feedback Linearization Controller Design 27
2.5.1 Problem Formulation 27
2.5.2 Main Results 29
2.5.3 Illustrative Examples 31
Chapter 3 Stabilization of Window-Based TCP/AQM System 39
3.1 Introduction 39
3.2 Nonlinear Window-Based TCP Dynamics 40
3.3 GA-Based PID Controller Design 42
3.3.1 Problem Formulation 42
3.3.2 Main Result 43
3.3.3 Illustrative Examples 47
3.4 State Feedback Controllers Design 60
3.4.1 Problem Formulation 60
3.4.2 Main Results 62
3.5 Observer-Based Controllers Design 63
3.5.1 Problem Formulation 63
3.5.2 Main Results 64
3.5.3 Illustrative Examples 67
Chapter 4 Robust Controller Design of Stochastic TCP/AQM System 77
4.1 Introduction 77
4.2 Robust Stochastic Stabilization 79
4.2.1 Problem Formulation 79
4.2.2 Main Result 83
4.3 Robust H∞ Stochastic Control Design 88
4.3.2 Main Results 88
4.3.3 Illustrative Examples 91
Chapter 5 Implementation of AQM Controller by Linux Platform 100
5.1 Introduction 100
5.2 Implementation of AQM as Kernel Modules in Linux 101
5.3 An Illustrative Example 103
Chapter 6 Conclusions and Future Works 108
6.1 Conclusions 108
6.2 Future Works 110
 V. Jacobson, “Congestion avoidance and control,” Proceedings of ACM SIGCOMM’88, pp.314-329, 1988.
 R. Srikant, The Mathematics of Internet Congestion Control, Cambridge, MA: Birkhauser, 2004.
 S. Floyd and V. Jacobson, “Random early detection gateways for congestion avoidance,” IEEE/ACM Transactions on Networking, vol. 1, pp. 397-413, 1993.
 D. Lin and R. Morris, “Dynamics of random early detection,” Proceedings of ACM SIGCOM’97, pp. 127-137, 1997.
 T. J. Qtt, T. V. Lakshman and L. H. Wong, “SRED: stabilized RED,” Proceedings of IEEE INFOCOM’99, pp. 1346-1355, 1999.
 S. Floyd, R. Gummadi and S. Shenker, “Adaptive RED: an algorithm for increasing the robustness of RED’s active queue management,” , 2001.
 W. Feng, D. Kandlur and K. Shin, “Stochastic fair blue: a queue management algorithm for enforcing fairness,” Proceedings of IEEE INFOCOM’01, pp. 1520-1529, 2001.
 S. Athuraliya, S. Low, V. Li and Q. Yin, “REM: Active Queue Management,” IEEE Network Magazine, vol. 15, pp. 48-53, 2001.
 S. Low, F. Paganini, J. Wang, S. Adlakha and J. Doyle, “Dynamics of TCP/RED and a scalable control,” Proceedings of IEEE INFOCOM’02, pp. 1079-1092, 2002.
 S. Kunniyur and R. Srikant, “Analysis and design of an adaptive virtual queue (AVQ) algorithm for active queue management,” Proceedings of ACM SIGCOM’01, pp, 123-134, 2001.
 V. Misra, W. B. Gong and D. Towsley, “Fluid-based analysis of a network of AQM routers supporting TCP flows with an application to RED,” Proceedings of ACM/SIGCOM, pp.151-16, 2000.
 C. V. Hollot, V. Misra, D. Towsley and W. B. Gong, “On designing improved controllers for AQM routers supporting TCP flows,” Proceedings of IEEE INFOCOM, pp.1726-1734, 2001,.
 C. V. Hollot, V. Misra, D. Towsley and W. B. Gong, “Analysis and Design of Controllers for AQM Routers Supporting TCP Flows,” IEEE Transactions on Automatic Control, vol. 6, pp. 945-959, 2002.
 F. Y. Ren, C. Lin and X. H. Yin, “Design a congestion controller based on sliding mode variable structure control,” Computer Communications, vol. 28, pp. 1050-1061, 2005.
 H. Y. Zhang, B. H. Liu and W. H. Dou, “Design of a robust active queue management algorithm based on feedback compensation,” Proceedings of ACM/SIGCOMM’03, pp.277-285, 2003.
 C. G. Wang, J. C. Liu, B. Li, K. Sobhraby and Y. T. Hou, “LRED: a robust and responsive AQM algorithm using packet loss ratio measurement,” IEEE Transactions on Parallel and Distributed Systems, vol. 18, pp. 29-43, 2007.
 S. M. M. Alavi and M. J. Hayes, “Robust active queue management design: a loop-shaping approach,” Computer Communications, vol. 32, pp. 324-331, 2009.
 N. Bigdeli and M. Haeri, “Predictive functional control for active queue management in congested TCP/IP networks,” ISA Transactions, vol. 48, pp. 107-121, 2009.
 D. Wang and C. V. Hollot, “Robust analysis and design of controllers for a single flow,” Proceedings of ICCT, pp.276- 280, 2003.
 Y. Fan, Z. P. Jiang and S. S. Panwar, “An adaptive control scheme for stabilizing TCP,” Proceedings of 5th World Congress on Intelligent Control and Automation, pp.1410-1414, 2004.
 S. Manfredi, M. D. Bernardo and F. Garofalo, “Reduction-based robust active queue management control,” Control Engineering Practice, vol. 15, pp. 177-186, 2007.
 S. T. Guo, X. F. Liao and C. D. Li, “Stability and Hopf bifurcation analysis in a novel congestion control model with communication delay,” Nonlinear Analysis: Real World Application, vol. 9, pp. 1292-1309, 2008.
 S. T. Guo, G. Feng, X. F. Liao and Q. Liu, “Novel delay-range-dependent stability analysis of the second-order congestion control algorithm with heterogonous communication delays,” Journal of Network and Computer Applications, vol. 32, pp. 568-577, 2009.
 S. T. Guo, X. F. Liao, Q. Liu and H. X. Wu, “Linear stability and Hopf bifurcation analysis for exponential RED algorithm with heterogeneous delays,” Nonlinear Analysis: Real World Application, vol. 9, pp. 2225-2245, 2009.
 F. Kelly, Mathematical modeling of the Internet, In Mathematics Unlimited-2001 and Beyond, (Editors B. Engquist and W. Schmidt), pp. 685-702, 2001.
 P. Yan, Y. Gao and H. Özbay, “A variable structure control approach to active queue management for TCP with ECN,” Proceedings of the Eighth IEEE Symposium on Computers and Communications, pp. 1005-1011, 2003.
 X. Chang and J. K. Muppala, “An integral sliding mode based AQM mechanism for stable queue length,” Proceedings of IEEE 2004 Global Telecommunications Conference, pp. 1698-1702, 2004.
 J. B. Gao. N. S. V. Rao, J. Hu and J. Ai, “Quasiperiodic route to chaotic dynamics of Internet transport protocols,” Physical Review Letters, vol. 94, pp. 198702.1-198702.4, 2005.
 C. Li, G. Chen, X. Liao and J. Yu, “Hopf bifurcation in an Internet congestion control model,” Chaos, Solitons and Fractals, vol. 19, pp. 853-862, 2004.
 Z. F. Wang and T. G. Ghu, “Delay induced Hopf bifurcation in a simplified network congestion control model,” Chaos, Solitons and Fractals, vol. 28, pp. 161-172, 2006.
 H. Y. Yang and Y. P. Tain, “Hopf bifurcation in REM algorithm with communication delay,” Chaos, Solitons and Fractals, vol. 25, pp. 1093-1105, 2005.
 S. T. Guo, X. F. Liao, Q. Liu and C. D. Li, “Necessary and sufficient conditions for Hopf bifurcation in exponential RED algorithm with communication delay,” Nonlinear Analysis: Real World Application, vol. 9, 1768-1793, 2008.
 D. W. Ding, J. Zhu and X. S. Luo, “Hopf bifurcation analysis in a fluid flow model of Internet congestion control algorithm,” Nonlinear Analysis: Real World Application, vol. 9, pp. 824-839, 2009.
 L. Chen, X. F. Wang and Z. Z. Han, “Controlling chaos in Internet congestion control model,” Chaos, Solitons and Fractals, vol. 21, pp. 81-91, 2004.
 C. L. Liu and Y. P. Tian, “Eliminating oscillations in the Internet by time-delayed feedback control,” Chaos, Solitons and Fractals, vol. 35, pp. 878-887, 2008.
 N. Bigdeli and M. Haeri, “Time-series analysis of TCP/RED computer network, an empirical study,” Chaos, Solitons and Fractals, vol. 39, pp. 784-800, 2009.
 S. A. Al-Shamali, O.D. Crisalle and H. A. Latchman, “An approach to stabilize linear systems with state and input delay,” Proceedings of American Control Conference, pp. 875-880, 2003.
 Z. Artstein, “Linear Systems with Delayed Controls: A Reduction,” IEEE Transaction on Automatic Control, vol. 27, pp. 869-879, 1982.
 Y. Y. Cao, Z. Lin and T. Hu, “Stability analysis of linear time-delay systems subject to input saturation,” IEEE Transactions on Circuits and Systems-I: Fundamental Theory and Applications, vol. 49, pp. 233-240, 2002.
 V. L. Kharitonov, “Robust Stability Analysis of Time Delay Systems: A Survey,” Annual Reviews in Control, vol. 23, pp. 185-196, 1999.
 S. I. Niculescu, J. M. Dion and L. Dugard, “Robust Stabilization for Uncertain Time-Delay Systems Containing Saturating Actuators,” IEEE Transactions on Automatic Control, vol. 5, pp. 742-747, 1996.
 C. K. Chen, T. L. Liao and J. J. Yan, “Active queue management controller design for TCP communication networks: variable structure control approach,” Chaos, Solitons & Fractals, vol. 40, pp. 277-285, 2009.
 T. L. Liao, C. K. Chen, Y. Y. Hou, J. J. Yan, “Design of active queue management algorithms for TCP networks: nonlinear output feedback approach” submitted for publication to Mathematics and Computers in Simulation, 2009.
 C. K. Chen, H. H. Kuo, J. J. Yan, T. L. Liao, “GA-based PID active queue management control design for a class of TCP communication networks,” Expert System with Applications, vol. 36, pp. 1903-1913, 2009.
 C. K. Chen, Y. C. Hung, T. L. Liao, J. J. Yan, “Design of robust active queue management controllers for a class of TCP communication networks,” Information Sciences, vol. 177, pp. 4059-4071, 2007.
 H. K. Khalil, Nonlinear Systems, Macmillan Publishing Company, New York, 1992.
 K. Gu, V. L. Kharitonov and J. Chen, Stability of Time-delay Systems, Massachusetts: Birkhauser, 2003.
 S. Boyd, L. El Ghaoui, E. Feron and V. Balakrishnan, Linear Matrix Inequalities in System and Control Theory, SIAM, Philadelphia, PA, 1994.
 C. K. Chen, J. J. Yan, T. L. Liao, “Robust control for a class uncertain stochastic TCP/AQM system: an LMI-based approach” submitted for publication to Information Sciences, 2009.
 B. Bandyopadhyay, S. Janardhanan, Discrete-time sliding mode control, Springer, 2006.
 V. I. Utkin, Sliding Mode and their Applications in Variable Structure Systems, Mir Editors, Moscow, 1978.
 U. Itkis, Control System of Variable Structure, Wiley, New York, 1976.
 UCB, LBNL, VINT, Network Simulator. .
 M. Krstic, I. Kanellakopoulos and P. V. Kokotovic, Nonlinear and Adaptive control design, John Wiley and Sons, 1995.
 J. J. E. Slotine and W. Li, Applied Nonlinear Control, Prentice-Hall, Englewood Cliffs, New Jersey, 1991.
 D. E. Goldberg, Genetic algorithm in search, optimization, and machine learning, reading. MA: Addison Wesley, 1989.
 J. M. Johnson and Y. Rahmat-Samii, “Genetic algorithms in engineering electromagnetics,” IEEE Antennas and Propagation Magazine, vol. 39, pp. 7-21, 1997.
 M. Srinivas and L. M. Patnaik, “Adaptive probabilities of crossover and mutation in genetic algorithm,” IEEE Transactions on Systems, Man and Cybernetics, vol. 24, pp. 656-667, 1994.
 Y. J. Cao, “Eigenvalue optimization problems via evolutionary programming,” Electronics Letters, vol. 33, pp. 642-643, 1997.
 S. Anton, The Control Problem, Prentice-Hall, New York, 1992.
 C. Peng and Y. C. Tian, “Network control of linear systems with state quantization,” Information Sciences, vol. 177, pp. 2763-5774, 2007.
 B. M. Miller, “Optimization of queuing system via stochastic control,” Automatica, vol. 45, pp. 1423-1430, 2009.
 F. Zheng and J. Nelson, “An approach to congestion control design for AQM routers supporting TCP flows in wireless access networks,” Computer Networks, vol. 51, pp. 1684-1704, 2007.
 F. Zheng and J. Nelson, “An approach to congestion control design for AQM routers supporting TCP flow,” Automatica, vol. 45, pp. 757-763, 2009.
 S. Manfredi, M. D. Bernardo and F. Garofalo, “Design, validation and experimental testing of a robust AQM control,” Control Engineering Practice, vol. 17, pp. 394-407, 2009.
 R. Z. Khasminiskii, Stochastic Stability of Differential Equations, Sijthoff and Noordhoff, Alpen and Den Rijn, Holland, 1980.
 N. Gahinet, A. Nemirovski, A. J. Laub and M. Chilali, LMI Control Toolbox for use with MATLAB, Boston: The MathWorks, 1995.
 T. Azuma, H. Naito and M. Fujita, “Experimental verification of stabilizing congestion controllers using the network testbed,” Proceedings of American Control Conference, pp. 1841-1846, 2005.
 P. Sarolahti and A. Kuznetsov. “Congestion control in Linux TCP,” Proceedings of the FREENIX Track: 2002 USENIX Annual Technical Conference, pp. 49-62, 2002.
 W. Almesberger, “Linux Network Traffic Control - Implementation Overview,” Technical Report, EPFL, 1998.
 Iperf, .